FIG. 3 is a sectional view showing a solar cell module formed by connecting a plurality of conventional solar cells which is disclosed in "GaAs Interconnect Design And Weld Technology", IEEE PVSC-1985, page 633. In FIG. 3, a solar cell comprises an n-type GaAs layer 2 and a p-type GaAs layer 3 disposed on an n-type GaAs substrate 1 and a cover glass attached thereto with a first adhesive 4. To interconnect these solar cells, an upper electrode of a first solar cell is connected to a lower electrode of a second solar cell with an interconnector 6. An upper electrode of the second solar cell is connected to a lower electrode of a third solar cell, and so forth. In this way, the upper electrode on one solar cell is connected to the lower electrode of the adjacent solar cell by the interconnector 6, whereby a predetermined number of solar cells are connected in series. These connected solar cells are arranged and mounted on a honeycomb board 8 with a second adhesive 7, completing the solar cell module.
Since the conventional solar cell is constructed as described above, when a solar cell is formed by connecting a plurality of solar cells in series, the solar cells are separate and the degree of freedom in designing the layout is low. In addition, since the p side electrode and the n side electrode are formed on the upper and lower surfaces of the solar cell, respectively, it is necessary to connect the upper electrode of one solar cell to the lower electrode of the adjacent solar cell to make a seris connection. However, it is difficult to connect two electrodes with the interconnector 6 because there is a large difference in the positions of the planes of the interconnection locations due to the thickness of the solar cells. The resulting structure with the interconnector 6 is complicated.
In addition, physical stress, such as heat generated at the time of interconnecting the solar cells, is applied to the solar cell, resulting in degradation of electrical characteristics of the solar cell.
Solar cells that avoid the difference in planes of interconnection and simplify the connection of solar cells are disclosed in Japanese Published Patent applications 64-82570, 64-82571, and 63-211773. In the structure disclosed in those publications, a through hole is formed in a substrate and an electrode on a front surface of the substrate reaches the rear surface of the substrate through the substrate and is connected to an electrode on the rear surface of the substrate. In this case, however, it is necessary to cover the pn junction with an insulating film to pass the electrode on the front surface of the substrate to the rear surface. The formation of that insulating film is difficult. Furthermore, it is technically difficult to pass the electrode on the front surface of the substrate to the rear surface thereof.